Near-field communication (NFC), which employs wireless coupling via time-varying electromagnetic fields is increasingly employed.
Various applications are conceivable, where for example a wireless bi-directional data link is established between a remote unit and a stationary unit. Applications include payload data transfer, identification and authentication, personalization of the remote unit, cashless paying, etc. Typical NFC transceivers are designed in order to provide a wireless coupling up to distances of roughly 5-10 cm. The operation frequency is typically 13.56 MHz. Such transceivers employ antennas comprising substantially planar conducting paths which are arranged, for example, in a circular or winding manner in order to provide a large inductive coupling to a time-varying alternating current (AC) magnetic field (H-field). The coupling with the remote antenna is then achieved via a spatially decaying, time-varying electromagnetic field. In particular, the coupling may only exist up to a certain distance between the two antennas as defined by the decay.
Moreover, typical antennas have directional emission characteristics that provide a large inductive coupling to an AC H-Field and therefore wireless coupling in a direction substantially perpendicular to the plane as defined by the mostly planar conducting paths. Here, the antenna may be sensitive in a narrow or wider solid angle centered around the direction. Electronic circuitry is coupled to the conducting paths and allows for controlling of the transceiving (i.e., driving current through the conducting paths and thereby generating the AC H-field, as well as measuring current driven through the conducting paths by a remotely generated AC H-field).
However, because typically the wireless coupling is restricted to a range of 5-10 cm and a comparably narrow solid angle around the direction, the flexibility in the arrangement of the antenna is limited when at the same time coupling with a low likelihood of transmission errors is desired. In particular, if the electric circuitry for controlling the transceiver is spacious, a degraded wireless coupling strength may be obtained due to restrictions imposed on the placement of the antenna and the connected electric circuitry. This may result in increased rate of failure for data transmission.
Accordingly, a need exists to provide an antenna assembly for providing wireless coupling to a remote antenna with increased flexibility of the arrangement. In particular, a need exists for providing an antenna assembly which allows for stronger wireless coupling to the remote antenna and therefore a reduced rate of failure in wireless data transmission by means of the wireless coupling.